Magic Methods
This keyword goes against the principles of object oriented methodology. No class is so sacred it can't be allowed to evolve. No programmer is so omniscient to know what will be needed 5 years (let alone 5 minutes) from release. 'Final' should be disabled and depreciated.
Final Keyword
PHP 5 introduces the final keyword, which prevents child classes from overriding a method by prefixing the definition with final. If the class itself is being defined final then it cannot be extended.
Example#1 Final methods example
<?php
class BaseClass {
public function test() {
echo "BaseClass::test() called\n";
}
final public function moreTesting() {
echo "BaseClass::moreTesting() called\n";
}
}
class ChildClass extends BaseClass {
public function moreTesting() {
echo "ChildClass::moreTesting() called\n";
}
}
// Results in Fatal error: Cannot override final method BaseClass::moreTesting()
?>
Example#2 Final class example
<?php
final class BaseClass {
public function test() {
echo "BaseClass::test() called\n";
}
// Here it doesn't matter if you specify the function as final or not
final public function moreTesting() {
echo "BaseClass::moreTesting() called\n";
}
}
class ChildClass extends BaseClass {
}
// Results in Fatal error: Class ChildClass may not inherit from final class (BaseClass)
?>
add a note
User Contributed NotesFinal Keyword
someone3x7 at hotmail dot com
06-Mar-2008 02:32
06-Mar-2008 02:32
slorenzo at clug dot org dot ve
31-Oct-2007 03:13
31-Oct-2007 03:13
<?php
class parentClass {
public function someMethod() { }
}
class childClass extends parentClass {
public final function someMethod() { } //override parent function
}
$class = new childClass;
$class->someMethod(); //call the override function in chield class
?>
penartur at yandex dot ru
22-Mar-2007 05:39
22-Mar-2007 05:39
Note that you cannot ovverride final methods even if they are defined as private in parent class.
Thus, the following example:
<?php
class parentClass {
final private function someMethod() { }
}
class childClass extends parentClass {
private function someMethod() { }
}
?>
dies with error "Fatal error: Cannot override final method parentClass::someMethod() in ***.php on line 7"
Such behaviour looks slight unexpected because in child class we cannot know, which private methods exists in a parent class and vice versa.
So, remember that if you defined a private static method, you cannot place method with the same name in child class.
liumr at ustc dot edu
11-Mar-2007 02:29
11-Mar-2007 02:29
this key word can describe a class or a class member function